The official website for Al Gore's Inconvenient Truth movie promotes CFL light bulbs, all types of which contain small amounts of mercury. When a bulb breaks it can release that dangerous element into the home and perhaps even lead to soil or water pollution.

From climatecrisis.net/takeaction/whatyoucando:

Replace a regular incandescent light bulb with a compact fluorescent light bulb (cfl)
CFLs use 60% less energy than a regular bulb. This simple switch will save about 300 pounds of carbon dioxide a year. If every family in the U.S. made the switch, we’d reduce carbon dioxide by more than 90 billion pounds! You can purchase CFLs online from the Energy Federation.

Turning to that "Federation":

All fluorescent lamps contain a small amount of mercury, generally about 5 milligrams or less. These compact fluorescent lamps all contain 2 milligrams of mercury or less, making them particularly environmentally responsible relative to conventional compact florescents. Every fluorescent light bulb however, regardless of mercury content, should still be recycled at the end of its life, and not disposed of with other trash.

Indeed. And, what happens if you accidentally break one? The state of Maine has compiled a helpful guide. Unfortunately, it's in a 150+ page PDF file (link) listing all the disposal hazards of the bulbs, suggesting that people not vacuum up broken bulbs to avoid the mercury being vaporized, suggesting that the safest way to dispose of the glass shards be placed in a glass jar with a rubber seal, and on and on. And, they also go into the amount of mercury vapor expelled into the atmosphere when one breaks, which apparently can be "over 300 times the accepted level of the US Environmental Protection Agency (EPA)" (link).

Even NPR noticed the problem back in 2007 ("CFL Bulbs Have One Hitch: Toxic Mercury", link), albeit mostly from the perspective of there not being a recycling infrastructure. See also this and this.

CFLs are no more dangerous than standard linear fluorescent bulbs which have been in use in homes, businesses, and schools for decades. The large majority of CFLs contain significantly less mercury than their linear cousins in fact. Their lower energy consumption also reduces overall environmental mercury emissions stemming from power generation at power plants.

Thu, 02/12/2009 - 13:48

Mary

uh, beg pardon....you need to learn what happens when one breaks...like leave the room for at least 5 minutes....don't touch it...clean up very carefully.....(yeah like kids at home will do all this???) Some contend the lights themselves cause health problems..... Then to top it off...all together they pose yet another hazard in that all that 'tiny bit of mercury ' has to be dealt with....just adding one more problem to replace another.....Government sure is SMART! ----By the way enjoy your extra $13 a week thanks to the new Trillion dollar stimulus bill.....What a JOKE!!